Process and apparatus for drying.



E. P. BUTTS.

PROCESS AND APPARATUS FOR D RYING.

APPLICATION FILED SEPT- 1 I, 1915- 1,212,014. Patented Jan. 9,1917.

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I WITNESS IN V EN TOR.

fwd/931x553 EBY A TTOR NE Y.

.UNITED STATES r TEuT OFFICE.

EDWARD r. Burrs,- or sPaINGrIELn,"mnssncnusnrrs.

PROCESS AND APPARATUS FOR DRYING,

- To all whom it may concern.-

Be it known that I, EDWARD P.. BUT'rs, a citizen of the United States of America, residing in the city of Springfield, county of Hampden, and State of Massachusetts, have invented certain new and useful Improvements in Processes and Apparatus for Drying, of which the followingis a specification.

This invention relates to improvements in drying processes.

Specifically, it is designed for causing the web of paper, as it leaves the'last drying drum of the paper drying machine, to retain a definite quantity of moisture. v

In common practice paper is dried by adinittinglive or exhaust steam, or'both, to

the drying cylinders. Attempts have been made to control the resultant degree of dryt e amount of moisture inthe web as it leaves the last dryin drum or cylinder. By taking advantage 0 the change in the electric conductivity of the web of paper, I employ suitable electric connections and electro-magnetic devices for operating the valve which opens and closes the connection between-the boiler, or othersource of steam supply, to the drying rolls ondrums' in order to maintain the drums at a temperature which will cause the web of paper, as

it leaves the last drum, to contain the desired percentage of mo sture. It is a well own fact that when there is a large percentage of moisture in the-web of paper, there is greater electric conductivity than when the paper is drier, since dry paper forms a high resistance to the free passage of the electric current therethrough.

he accompanying drawing of which only one figure is shown, clearly illustrates the principle of my invention and apparatus for carryin out my invention. ferring to this gure, the framework Specification of Letters Patent.

one means orof the machine is indicated at 1, the drying: rolls or drums of which several are shown,

are indicated at 2.

e steam pipe connection, shown conventionally, is indicated at 3, and a suitable valve for varying the flow of the steam through the pipe 3 is indicated at 4.

Patented Jan. 9,1911; Application filed September 11, 1915. Serial No. 50,164. I I

he web of paper as it leaves the last drying drum 2 is indicated at 5. This web composed of some material that conducts the electric current readily, preferably with central Width'contact faces suiting most Widths of web. v

8 is the usual tension roll under which the web. passes after leaving the roll '7. The usual spring, indicated 21159, is employed for impartin the desired tension to the web. A suitab e source of electric current is supplied at the point 10. T is current controls the movement of the armature 11 to which an arm 12 is rigidly or integrall) connected. The arm 12 an armature 11 are pivotally mounted at 12. he armature 11 and arm 2 are therefore rocked or moved about dicated at 13.

14 is a wire connected to one terminal of the electro-magnet 13 which leadsto a Second electro-magnet 15.v C

has electric connection therewith by means of the brush 18 that is in electric contacts with the shaft of the roll 7. 19 designates a second brush that pivot 12 by means of an electro-magnet, in-

has an electric contact with the shaft of the roll 6 to which the wire terminal of the valve 4 to the contact point 23with which the spring arm 24 engages. Connected to the wire 14 is a shunt wire 25 that extends to the arm 12.

minal 23 1 .The operation'of the device is as follows spring 26 'is attached to the arm 12 and normally holds the spring 24 in contact with the tere Current from the source of energy at 10" energizes the magnet 13 and normally flows the source of energy.

- source of energy,

' be maintained at through the wires 25, arm 12, wire 22, electric valve 1-, and wire 21 back to the it also normally flows by means of the wire 14, magnet 15, rheostat 16, wire 17, brush 18, r0117, to the web of paper 27, which-extends between the rolls 6 and 7, and thence by the wire 20 back to The variation in moisture of that portion of the web of paper indicated at 27 determines the strength of current flowing through the electro-ma-gnets 13 and 15. The rheostat arm 28 is adjustable for the purpose of determining the correct strength of current that should flow through the magnet 15 in order to open the circuit at the point 23, or, in other words to maintain the valve 4 open the correct amount, whereby the drying drums 2 will the proper temperature. If, for any reason the web of paper, indicated at 27, is too moist, whereby a stronger current is permitted to flow through the electro-magnets 13 and 15, the arm 1.2 and armature 11 which move therewith will be strongly attracted by the electromagnets 13 and 15 and the contact 23 will be opened causing the valve a to be opened to a greater extent in order to increase the supply 0 steam and raise the temperature of the drying drums 2. This condition will be maintained until the web of paper, as it passes between the pulleys 6 and 7 contains less moisture, when the resistance of the web 27 will be increased, thus cutting-down the current flowing through the magnets 13 and 15, The spring 26 will then operate against the action of the electro-magnets to again close thecontact 23, whereby current will again flow from the source of energy at 10, wire 25, arm 12, and wire 22, to the valve 4, causing the same to close again and thus lower the temperature of the drying drum 2. It will thus be seen that by means of the rheostat arm 28, the operation of the movements of the armature 11 and the integral arm 12 can be very adcurately controlled and in turn, the operation of the valve 4, to admit or shut off more or less steam to the drying drum 2, the controlling means being based primarily on the resistance to the flow of the electric current through the web 27, since the current constantly flows through the web. That is to say, when there is considerable moisture the resistance or the web is lower, and when there is a small percentage of moisture the resistance is increased, or the flow of current is in? versely proportioned to the percentage of moisture in the web varying inversely as the steam supply.

It is obvious that either one of the electro-magnets 13 or 15 could be dispensed with but 1 have shown the two electro-magnets for the purpose of rendering the device more sensitive to the small variation of current.

. offlan electro-magnet interposed in 'nections from ObVlOUS that an ammeter may be mserted in either of the wires 17 01*20 in order that the machine attendant may know exactlyjust what the strength of current is when the moisture in the web is the proper amount. Such an instrument is conventionally indicated at 30 in the wire 20 and will materially assist the attendant when the machine is first started and perimenting. It is, of course, apparent that the location of my improvement is not necessarily confined to the precise position as shown, which is directly back of the last drying cylinder, as the same may, if desired, be located between any two of the dry ing cylinders.

Having thus described my invention, what I claim is- 1. In a paper making machine the combination with the drying drums thereof, a pair of spaced supports for receiving the web of paper, means for conducting the web of paper across a pair of spaced supports, the source of electrical energy, connections therefrom to the pair of supports for permitting an electric current to flow through the web of paper between said supports, an electromagnetically controlled valve to vary the supply ing drums, electrical connections for controlling the operation of the valve, means in the connections between the supports and said valve for controlling the flow of current to said valve dependent upon the strength of the current flowing through the web of paper on said supports.-

2. Tn a paper making machine, the combination with the drying drums, spaced supports to receive the web of paper as it leaves a drying drum, a source of electrical energy, connections therefrom to the spaced supports for permitting the electric current to flow through the web of paper between said supports, an electrically controlled shut-oft device for varying the flow of the heating medium to the drying drums, means for opening and closing the connections to said shutthe conthe source of energy to the spaced support for controlling said means, the movements of said controlling means depending upon the variation of moisture in the movable web of paper as it passes through the web of paper from one support to the other, whereby the quantity of heat supplied to the drying drums is automatically varied, as described.

3. In a machine of the kind described, the combination with the heating drums, means to support the web of paper as it passes from a drying drum, a source of electric energy, connections therefrom to said means for avoid delays in er;-

electrically operated valve causing the current to pass through the web from the support, electro-magnetic means in the connections and controlled by the curan electric valve for controlling maintained for be automatically dryness of the the moisture or 4. In a device for controlling the supply of steam to the heating drums of a paper making machine, comprising in combination supporting devices for receiving the Web 0 paper as 1t leaves the last drying source of electric ener connections from the supporting devices to said source, an for controlling the supply of steam to the drums, connections from the valve to the source of energy electromagnetic devices in the first-name connections for controlling said valve, the operation of netic devices being de tric conductivity of t the operation of the electro-magendent upon the elece moving Web of paper on the supporting devices.

5..In a machine of the kind described, for automatically maintaining the electric conductivity of a, Web of paper constant, means to support a definite length of the web, a

the supply of heat to the he supports will controlling means.

6. The method of drying a moving web of material which consists in terial to the action of a d supply of the drying medium inverse such electrical conductivity.

7. The method of drying a moving web of material which consists in subjecting the material to the action of a drying medium,

electrical conductivit the dryin medium inversely to such electrical conductivity.

A inethod material electrical conductivity of the web as it passes from the influence of the drying mechanism and controlling the drying medium by varying the supply of the drying medium in direct proportion of the web.

to the electrical conductivity EDWARD P. BUTTS. 

